Greetings Kalamondin, DavidJ
David, thank you for providing that link. I've read the discussion with great interest and have supplemented my knowledge of taiji language and terms a lot.
Kalamondin, I don't pretend to be absolutely precise in description of these terms. It's only my personal understanding which I found very applicable in my pushing hands practice.
I would say that the main idea is to use softness to overcome hardness.
Yang tradition (probably Yang Banhou) explaining Zhan, Nian, Lian, Sui states about Zhan:
Zhan zhe, ti shang ba gao zhi wei ye.
I would render this sentence as
"Raising up and uprooting high is called Zhan"
This, in my understanding, means:
"Raising up his root internally and uprooting him through upper section of his body is Zhan".
In pushing hands practice it means: approaching upper section of his body you provoke the wave of resistance in his body and raising of his roots from earth depth up to earth surface. Then if you have pushing hand experience you'll find the way to dump him down. It may be done by pushing or by yielding. Personally I prefer pushing. If your opponent has experience in pushing hands and escaped from your attack you proceed by Nian, Lian and Sui which deal with different directions.
[This message has been edited by Yury Snisarenko (edited 11-03-2004).]